1. Field of the Invention
This invention relates to the provision of an improved tamper-resistant closure for a container and to an improved tamper-resistant container and closure assembly.
2. Background Art
Tamper-resistant closures have been known for some years for example closures known under our Registered Trade Mark JAYCAP are very popular. JAYCAP closures consist of a cap part, a tear band, an anchor band and a hinge connecting the cap part to the anchor band. Lines of weakness connect the cap part to the tear band and the tear band to the anchor band so that the tear band can be torn away easily. JAYCAP closures work extremely well when the closures are made from an easily tearable plastics material such as low density polyethylene but are not so effective when attempts are made to make JAYCAP closures from a stronger plastics material such as high density polyethylene or polypropylene that is not readily tearable.
To make tamper-resistant closures from the stronger materials has therefore involved special problems and a solution that has been successfully adopted is to connect the various parts of the closure together by spaced apart frangible nibs or tongues leaving spaces in between. We have adopted that technique in the manufacture of closures known under our Registered Trade Mark JAYPOUR. However, experience has shown that there are one or two drawbacks in the use of the spaced apart nibs. Firstly, the spaces in between the nibs tend to collect dust and, although the contents can be effectively sealed from the spaces, customers do not like to see dust collecting in that way because it looks so unhygenic. Secondly, there is a moulding problem due to the fact that hot moulding plastics material is introduced into the mould e.g. at the top dead centre and flows outwards and downwards around the core pin, cooling and solidifying all the time. As the material reaches the lower part of the closure the material meets an obstruction forming the spaces between the nibs, the only flow paths being provided by the nib channels, and this sometimes leads to the production of a faulty tear band through incompletely filling. Attempts to do away with the nibs and to provide wafer thin lines of weakness have failed because the lines of weakness had to be so thin to permit tearing that in many cases the membranes did not exist at all. In addition, parts of the component beyond the failed membrane are usually malformed.